Beverage capsule

ABSTRACT

A capsule for use in a coffee machine having a brew chamber, which capsule is formed from a ductile metal such as aluminium. The capsule has a generally frusto-conical form with an upper surface and a lower surface, an annular flange being provided at the lower surface. An annular seal is provided on the annular flange having first and second layers, wherein the first layer comprises long, well-bound fibres of a cellulose material.

The invention relates to a beverage capsule for an espresso machine, inparticular for making espresso under high pressure.

Powered espresso machines are well known. The conventional espressomachine comprises a water chamber, a heating element adapted to heat thewater to around 95-98 C, which is then pumped under high pressure of 15to 19 bar to a filter holder or portafilter. Lower pressure systems alsoexist. The filter holder typically comprises a handle portion and aholder portion provided with two or three lugs that are adapted toengage in the installed position with the machine brewhead to where thewater is pumped. The holder portion is adapted to receive a filter,which is usually a metal bowl with a number of perforations through itsbottom. In use, the filter is filled with finely ground coffee and thewater is forced through the coffee at the high pressure generated by thepump to produce the espresso coffee which is collected in a cup placedunder the filter holder.

The classic coffee machine suffers from two potential drawbacks. Thefirst drawback is that ground coffee starts to lose its freshness andflavour after a few days and so for the optimum espresso, the user willalso need to have a coffee grinder. The other drawback is that the usedespresso coffee has to be removed from the filter, which can lead tomess as the grinds are fine.

This led to the development of ESE coffee pods, which can be used inmany espresso machines. Coffee pods are generally individually wrappedto maintain freshness and consist of a small pod made of a perforatedfilter paper which contains the coffee. The pod is placed in the filterholder and then disposed of after use. Coffee pods are convenient buthave to fit the filter holder and be placed correctly otherwise watercan leak around the edge.

This in turn lead to the development of capsule machines. The coffeecapsules for these machines are completely sealed. The capsule machinesdo not use the conventional filter holder. A capsule machine typicallyhas a two part mechanism. The first part receives the capsule and isprovided with an extraction surface upon which the capsule rests. Thesecond part is provided with a locking lever which is used to make thefirst and second parts integral. In use, the second part cuts the uppersurface of the capsule to allow water to enter the capsule and percolatedown through the capsule, where it exits through the lower surface ofthe capsule at multiple locations determined by the geometry of theextraction surface. An example of such a machine is disclosed in EP0870457 or WO2005/004683. Capsules in the known capsule coffee machinesare, in use, inserted into a capsule cage of the machine which holds thecapsule in position so that it may be cut by a cutting member.

Capsule machines have proved to be commercially very successful as theyare very convenient to use and produce a consistent product. However,each manufacturer's coffee machines and capsules are designed to workwith the manufacturers own brand. The most popular brand of capsule isNespresso®, which uses a sealed capsule made of aluminium. In use, thecapsule is clamped into position in the machine with a capsule cage partholding the capsule so that it can be cut by typically three prongs toenable water under pressure to enter the coffee capsule.

Aluminium has the considerable advantage that it is oxygen and waterimpermeable, which means that the coffee in the capsules has a longshelf life. Aluminium however also suffers from several major drawbacksin that the aluminium is easily deformed during the filling and packingstage and it is difficult and expensive to produce a reliable seal onthe capsule rim. The only known seal that works is a silicone elastomerdisclosed in EP1654966 despite significant research effort. In thesecapsules the edge of the aluminium rim is rolled over where the frontfoil seal is attached. The known solutions to these problems furtherrequire an extremely high capital investment beyond most companies.

It has been proposed to use raised ribs formed by pushing out materialfrom the capsule rim. These seals are functional but reduce theeffective sealing area on the front circumference of the capsule wherethe capsule is sealed with a foil. This results in unacceptably highfailure rates of the foil seal so that the filled capsule degasses withthe consequence that the coffee becomes stale.

Attempts to use paper gaskets have also failed for several reasons.Known paper gaskets tend to delaminate due to the rapid depressurisationof the brew chamber, when the handle is lifted on the coffee machine,causing the laminate layers of the material to separate and becomedetached from the capsule. A further type of delamination occurs whenink printed onto the surface prevents pressure within the gasket fromescaping as it forms a waterproof barrier.

This delaminated gasket material can over time build up on the brewchamber within the machine and cause subsequent capsules to leak duringextraction and produce a short shot/insufficient extraction.

A further problem is that paper gaskets tend to burst as they do nothave sufficient wet strength to survive the high pressures that occurduring coffee extraction. The gasket disintegrates in small areasallowing water to escape and reducing pressure.

A further problem with aluminium capsules arises due to the puncture ofthe capsule foil to allow water to pass through the coffee forextraction. The size of the holes affects the flow rate of the waterinto and through the capsule with the larger the hole the greater theflow rate and the smaller the hole the lower the flow rate. Controllingthe flow rate is therefore important to the quality of the coffee as tooslow a flow rate results in over-extraction rendering the coffee bitterand too fast a flow rate results in too weak an extraction, so thecoffee lacks flavour.

The present invention therefore seeks to provide an improved coffeecapsule.

According to a first aspect of the invention there is provided a capsulefor use in a coffee machine in accordance with the features of claim 1,which machine has a capsule cage for retaining the capsule in anextraction position, wherein the capsule is formed from a ductile metal.

Preferred aspects of the invention are disclosed in the sub-claims.

The seal of the invention advantageously provides a good seal for thecapsule and is more easily recycled than the known silicone seals.

Exemplary embodiments of the invention will now be described withreference to the drawings, in which:

FIG. 1a shows schematically a cross section of a capsule

FIG. 1b shows schematically a cross section of the capsule interfacingwith machine blades

FIG. 1c shows schematically a brewhead of a coffee machine

FIG. 2 shows a perspective view of the capsule;

FIG. 3a shows a first layered seal

FIG. 3b shows a second layered seal

FIG. 4 shows a laminated structure of a seal

FIG. 5a shows schematically a first alternative structure

FIG. 5b shows scheamtically a second alternative structure

FIG. 1a shows a cross-section of capsule 1 having a generallyfrustoconical form for the main body 2. The upper end 3 of the capsulehas a second frustoconical section 4 with a smaller diameter than thelower end. The upper end 3 is further provided with an additionalfrustoconical indent 5 at the centre of the upper end 3. The capsule isprovided with a flange 7 at the end of main body 2 remote from the upperend 3.

To ensure that the capsule functions effectively in the wide range ofcapsule coffee machine on the market, the four dimensions marked V, W, Xand Y are critical and need to be used if problems with the insertionand ejection of the capsule in the machines is to be avoided.

FIG. 1b shows a further dimension on the capsule, namely A, which is thedistance between the capsule sealing surface to the surface of thecapsule interfacing with the machine blades at the top of the capsuleand FIG. 1c shows a dimension B, which is the distance between thecoffee machine brew head or capsule cage sealing surface and the tip ofthe blade 20. Dimension A varies with the thickness of the seal on theflange, whereas dimension B is determined by the capsule coffee machinedesign. The piercing depth of the blades is deduced by subtractingDimension B from Dimension A.

FIG. 2 shows a perspective view of the capsule, which is provided withan annular protruding surface 10 outwards from the upper surface. Theprotruding surface 10 is chamfered or inclined but could also be aradiused surface. The protruding surface 10 provides a steeper anglethan the surface 4 to the blades, which improves the entry of the blade.The flange 7 comprises an upstanding wall 8, which thereby forms agutter 9 between the wall of the capsule and the upstanding wall 8. Theupstanding wall 8 then bends back down towards the same side as theopening such that the distal end is substantially in the longitudinalplane of the capsule but below the gutter 9. The shape of the distal endforms an open hook. The open hook receives a seal to close the capsuleafter packing or filling. The open hook shape provides a plurality ofwebs at the rim of the flange which provide a degree of reinforcement sothat the foil can be easily attached to a capsule made of softer, moreductile materials such as aluminium.

The annular surface 10 is raised from the surrounding plane of thecapsule surface 12 by between 0.15 and 0.35 mm and in a particularlypreferred embodiment 0.25 mm. The surface has a width of around 0.2-0.3mm, to allow for tolerances between machines. The angle of the surfaceto the planar surface of the capsule is between 30 and 34° with theangle increasing from the centre to the to the edge of the capsule.Within the range of heights of the protruding surface, the blades of thebrew head maintain an incident angle of around 30° to the planar surfaceof the capsule 12. If the incident angle of the blades is greater thanaround 35° or less than around 25° there is a tendency for the capsuleto deform under the action of the blades rather than be pierced. Withinthe ranges of the specific embodiments, a hole size of between 0.95 and1.05 mm diameter can be achieved, which allows an optimal flow rate fora standard espresso grind.

A seal 9, having a generally annular form is provided on the flange withexemplary seal structures shown in FIGS. 3a, 3b and 4. Exemplary sealscontain a layer of chemical (sulphate) pulp or CTMP(chemi-thermomechanical pulp) or 3 layers with a layer of chemical(sulphate) pulp and CTMP (chemi-thermomechanical pulp). The chemicalpulping process produces long, well-bound fibres, which give thematerial high strength and water-resistant properties.

The material structure also provides good edge wick holdout. Edge wickdefines a resistance to liquid penetration along the exposed edge of aboard, which helps to maintain the strength and rigidity of the gasketin use.

PE: Exemplary Property Specification Thickness 200-595 (microns)Grammage (gsm) 150-550 Tear Resistance 3000-5000 (mN) Test method: ISO1974 Internal Bond ≥90 Strength (J/m²) Test method: T 596 Moisturecontent 7.0%-8.5% Test method: ISO 287 Edge wick (mm) ≤5 mm wicking Testmethod: Hot distance. Water 95° C., 10 minutes

A further exemplary embodiment shown in FIGS. 3a and 3b is a hybridlaminate option in which the hybrid concept can be a laminate of elasticmaterial (for example one of foam/plastic/silicon) and non elasticdeformable material (i.e. paper). The lamination can be 2 or more layerswhere paper is the outer or upper layer so it plastically deforms.

Residual water in the brewhead causes a small amount of swelling of thepaper or cellulose material when the coffee machine is in use, whichswelling enables a better engagement with castellations on the brewheadthereby improving the seal.

The seal can be retained in position either by adhesive or a mechanicalmeans.

In a first embodiment, the seal is fixed to the flange with an adhesive,in particular a starch based biodegradable adhesive having a melt rangearound 140 degrees, which is sufficiently above 100 degrees seen duringcoffee extraction, but low enough to activate during the short dwelltime during capsule filling. Using an elevated sealing head temperatureenables a temperature of 140 degrees to be reached in that short time.

In an alternative embodiment, the gasket can be applied with pressureand/or heat without using an adhesive. This could either be a dry heatprocess or it would be possible to use steam. As pressure and/or theheat is applied the gasket swages out and tightens around the internaldiameter, creating a tight fit over the capsule. The outer diameter alsoincreases, pushing the gasket against the rim of the capsule.

In a further alternative embodiment, it is possible to apply a liquidheat sealable adhesive directly to the board This can be used instead ofadhering a film to the board would be help reduce cost and improverecyclability. The liquid heat sealable adhesive is applied in one ormore coats. The first acts as a primer, the subsequent coat or coats areapplied to build up a level of thickness that is on the surface,ensuring not all the adhesive has been absorbed into the board. Anexemplary grammage for heat seal adhesive applied is 4 to 30 gsm.

For cosmetic reasons it is preferable to use a gasket that is colourmatched to the capsule. The known approaches suffer from the problemthat the gasket adheres to the Brew Chamber during/after extraction whenthe capsule is ejected. The reason for this is likely to be the inkssoften when exposed to the heat and pressure and re-activate (soften).Then when cooling, the ink and gasket stick to the brew chamber. Thiscan leave all or some of the gasket on the brew chamber, resulting inbuild-up which ultimately leads to leaks during extraction. The printedgasket may also prevent pressure release from gasket

In a preferred aspect the seal is made from a non-coated board or onlyon one side and ink is applied to the non coated side, for example tocolour match the seal to the capsule body. This approach advantageouslyallows the ink to soak into the core of the board, making delaminationless likely. Alternatively, it is possible to apply a pattern to the noncoated side, which breaks up the print layer into small pieces, allowingpressure to escape. If delamination does start, the pattern reduces thelikelihood of the delamination spreading. The pattern can comprisedots/hashed lines/wavy line etc. Aesthetically the pattern can be chosenso that the board looks fully printed.

This can be solved by laminating over the top of the printed surface asshown in FIG. 4, the ink is not in direct contact with the brew chamber.Therefore, even if it does re-activate, it cannot stick to the brewchamber.

The capsule wall is provided with flutes which extend over substantiallythe length of the side wall part 2 of the main body. The flutes arerecessed by between 0.1 and 0.3 mm from the maximum outer radius of theside wall 2. The flute may be between 0.5 and 10 mm wide. The flutes maybe substantially contiguously disposed in the side wall.

It has been surprisingly discovered that the provision of the flutesextending over a substantial part of the side wall 2 greatly increasethe strength of the capsule, which becomes much less likely to deform.The fluted design capsule requires a force of 20N to deform the side ofthe capsule by 2.0 mm, whereas known capsules require a force of 10N to15N. The force is applied using a 9.0 mm diameter pad, ⅓ up from thegasket sealing surface, in a direction normal to the axis of thecapsule. This greatly improves the ease of handling the capsule both inthe manufacture of the capsule and its filling. It is also less likelyto be damaged in transit. This will reduce wastage in capsule productionand facilitate the wider use of aluminium capsules which are preferableto plastic with respect to their recyclability.

In capsule of the invention the aluminium is between 0.075 to 0.125 mmthick.

FIG. 5a shows an alternative arrangement of the seal in which theannular seal 9 is provided with an annular groove or concave rib 15. Acorresponding annular groove 16 is formed on the annular flange of thecapsule. The annular groove 10 can receive the capsule cage of thecoffee machine.

FIG. 5b shows an alternative arrangement to that of FIG. 5a , in whichthe seal is provided with an annular protrusion or convex rib 17. Theannular flange is provided with a corresponding protrusion or rib 18. Inuse, the capsule cage of the coffee machine can engage on the protrusionto form a seal.

Although the capsule has been specifically described as being used tomake espresso coffee, it would be possible to use the capsule to makeother beverage capsules such as tea or chocolate.

1. A capsule for use in a coffee machine having a brew chamber, whichcapsule has a generally frusto-conical form with an upper surface and alower surface, an annular flange being provided at the lower surface,wherein an annular seal is provided on the annular flange comprising acellulose material such as paper that deforms plastically in use,wherein the annular seal comprises first and second layers, wherein thefirst layer comprises long, well-bound fibres.
 2. The capsule accordingto claim 1, wherein the second layer comprises an elasticallycompressible material.
 3. The capsule according to claim 1, wherein theseal further comprises a layer for adhesive for attaching the seal tothe capsule rim.
 4. The capsule according to claim 1, wherein the firstlayer is formed from chemical (sulphate) pulp or CTMP(chemi-thermomechanical pulp).
 5. The capsule according to claim 1,wherein the seal comprises a layer of a liquid heat sealable adhesive.6. The capsule according to claim 3, wherein the adhesive is starchbased biodegradable adhesive having a melt range around 140 degreesCelsius.
 7. The capsule according to claim 1, wherein the seal isapplied with pressure and/or heat without using an adhesive, wherein aspressure and/or the heat is applied the gasket swages out and tightensaround the internal diameter of the seal to fix the seal in position onthe capsule.
 8. The capsule according to claim 1, wherein the seal ismade from a non-coated board or only is only coated on one side and inkis applied to the non coated side.
 9. The capsule according to claim 1,wherein a pattern is applied to a or the non coated side of the seal,which breaks up the print layer into small pieces, thereby allowingpressure to escape.
 10. The capsule according to claim 8, wherein theseal is laminated over the top of the printed surface so that the ink isnot in direct contact with the brew chamber of a coffee machine.
 11. Thecapsule according to claim 1, wherein the edge wick is less than 5 mm inan edge wick test with Hot Water at 95° C. for 10 minutes.
 12. Thecapsule according to claim 1, wherein the seal has a tear resistance of3000-5000 mN and an internal bond strength of greater than or equal to90 J/m2.
 13. The capsule according to claim 1, wherein the seal isprovided with an annular groove for receiving the capsule cage orbrewhead of a coffee machine and thereby provide a sealing engagement.14. The capsule according to claim 1, wherein the seal is provided withan annular protrusion for engaging with the capsule cage or brewhead ofa coffee machine and thereby provide a sealing engagement.
 15. Thecapsule according to claim 13, wherein the flange is provided with acorresponding groove or protrusion.